This pilot feasibility study was designed to test the hypothesis that laser-induced transmyocardial channels could be created and provide augmentation of blood flow to an ischemic zone. Three laser systems were tested; carbon dioxide, argon and excimer. The first had too little power to penetrate the full thickness of the myocardium and created charred lesions. Argon passed through 1 mm fibers penetrated but charred. The excimer system was reliable and produced clean channels. Five dogs had the application of an ameroid constrictor to the left anterior descending coronary artery. Excimer lasing was performed. Collateral flow will be measured with the radioactive microspheres techniques. Biochemical and morphologic studies will be performed.